Manufacturing method for ink jet recording head chip, and manfuacturing method for ink jet recording head

ABSTRACT

A manufacturing method for a substrate for an ink jet head, including formation of an ink supply port in a silicon substrate, the method includes a step of forming, on one side of the substrate, an etching mask layer having an opening at a position corresponding ink supply port; a step of forming unpenetrated holes through the opening of the etching mask layer in at least two rows in a longitudinal direction of the opening; and a step of forming the ink supply port by crystal anisotropic etching of the substrate in the opening.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to a manufacturing method for an ink jetrecording head chip recording on recording medium by jetting ink, and amanufacturing method for an ink jet recording head.

Ink jet heads of the type which jet ink upward of the elements forgenerating the ink jetting pressure have long been known (hereafter,this type of ink jet head may be referred to as side shooter head). Thistype of ink jet head is provided with a substrate, and an ink jettingenergy generating portions which are on one of the primary surfaces ofthe substrate. The ink jetting energy generating portions are suppliedwith ink, from the back side, that is, the opposite surface of thesubstrate from the surface having the ink jetting energy generatingportions, through the through holes.

One of the manufacturing methods for this type of ink jet head isdisclosed in U.S. Pat. No. 6,143,190. More specifically, this patentdiscloses an ink jet head manufacturing method made up the followingsteps for preventing the formation of an ink jet recording head chip,the abovementioned through holes (common ink delivery channels) of whichare nonuniform in diameter:

(a) step for forming a sacrificial layer which can be etched acrossselected areas, on the areas of the surface of the substrate, whichcorrespond to the positions of the through holes;

(b) step for forming a passivation layer, which is resistant to etching,is formed in a manner to cover the sacrificial layer;

(c) step for forming an etching mask layer having such holes thatcorrespond in position to the strips of sacrificial layer on the backsurface of the substrate;

(d) step for anisotropically (with respect to crystal axes) etching thesubstrate through the openings until the strips of sacrificial layer areexposed;

(e) step for etching away the strips of sacrificial layer, from the sideexposed through the step for etching the substrate;

(f) step for completing the through holes by removing the portions ofthe passivation layer, which correspond in position to the throughholes.

Further, U.S. Pat. No. 6,107,209 discloses a method for anisotropicallyetching silicon (substrate formed of silicon), the surface azimuthalindex of which is 100. This anisotropic etching method is characterizedin that, before it etches a silicon substrate, it thermally processesthe silicon substrate so that the cross section of each cavity (commonink delivery channel) which results from the etching, will be shapedlike “< >”.

Further, U.S. Pat. No. 6,805,432 discloses another manufacturing methodfor an ink jet recording head. According to this method, a siliconsubstrate is dry etched, with a mask placed on the back surface of thesubstrate, and then, the substrate is anisotropically etched utilizingthe same mask. This manufacturing method can also effect common inkdelivery channels, the cross sections of which are also shaped like “<>”.

These manufacturing methods, which form cavities (common ink deliverychannels) having the “< >”-shaped cross section, are advantageous inthat they can manufacture an ink jet recording head, the substrate ofwhich is substantially smaller, more specifically, substantiallynarrower, than an ink jet recording head manufactured using an ink jetrecording head manufacturing method in accordance with the prior art. Inthe field of an ink jet recording head, in particular, the field of anink jet recording apparatus which employs a multicolor recording head,the substrate of which is provided with multiple common ink deliverychannels for delivering multiple inks, one for one, different in color,it is desired to manufacture an ink jet recording head chip, thesubstrate of which is even smaller than those of the ink jet recordinghead chips manufactured using the methods described above.

However, the method disclosed in U.S. Pat. No. 6,107,209 is limited interms of the distance from the bottom surface of a substrate to the apexof the “< >”-shaped cross section of the common ink delivery channel.Further, when this method is used, the cross-sectional shape, in whicheach common ink delivery channel will be finished, is affected by theoxygen concentration of the silicon substrate, making it difficult toreliably (accurately) mass-produce ink jet recording head chips.

On the other hand, in the method disclosed in U.S. Pat. No. 6,805,432,the mask used for dry etching is also used for wet etching. Thus, whenthis method is used, the width of the common ink delivery channel isdetermined by the width of the opening of the hole of the mask on theback surface of a substrate, and the depth by which the substrate is dryetched. Therefore, in order to form a common ink delivery channel, theopening of which is narrow, that is, a so-called narrow common inkdelivery channel, it is necessary to increase the depth to which thesubstrate is dry etched. Therefore, this method is problematic in thatit is inferior in terms of manufacture efficiency, because it takes moretime to make a hole in a silicon substrate by dry etching than by wetetching.

SUMMARY OF THE INVENTION

Thus, the primary object of the present invention is to provide an inkjet recording head chip manufacturing method for more reliablymass-producing ink jet recording head chips, at a higher level ofaccuracy than an ink jet recording head chip manufacturing method inaccordance with the prior art. More specifically, the primary object ofthe present invention is to manufacture an ink jet recording head chip,the common ink delivery channels of which are substantially narrowerthan that of an ink jet recording head chip manufactured with the use ofthe ink jet recording head chip manufacturing method in accordance withthe prior art, at a substantially higher level of precision and in asubstantially shorter length of time, compared to the method inaccordance with the prior art.

According to an aspect of the present invention, there is provided amanufacturing method for a substrate for an ink jet head, includingformation of an ink supply port in a silicon substrate, said methodcomprising a step of forming, on one side of said substrate, an etchingmask layer having an opening at a position corresponding ink supplyport; a step of forming unpenetrated holes through said opening of saidetching mask layer in at least two rows in a longitudinal direction ofsaid opening; and a step of forming said ink supply port by crystalanisotropic etching of said substrate in said opening.

The present invention makes it possible to reliably mass-manufacture inkjet recording head chips, at a substantially higher level of efficiency.

These and other objects, features, and advantages of the presentinvention will become more apparent upon consideration of the followingdescription of the preferred embodiments of the present invention, takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a part of an ink jet recording head chipin one of the preferred embodiments of the present invention.

FIG. 2 is a sectional view of the precursor of a typical ink jetrecording head chip, to which the ink jet recording head chipmanufacturing method in the first embodiment of the present invention isapplicable.

FIG. 3 is a sectional drawings showing Steps (A)-(D) in the ink jetrecording head chip manufacturing method, which is in the firstembodiment of the present invention.

FIG. 4 is a sectional view of an ink jet recording head chip, which hasonly a single row of pilot holes for forming a common ink deliverychannel, which is parallel to the lengthwise direction of the common inkdelivery channel.

FIG. 5a is a sectional drawing showing Steps (a)-(d) in the ink jetrecording head chip manufacturing method in the first embodiment, whichincludes Steps (a)-(d) shown in FIG. 3.

FIG. 5b is a sectional drawing showing Steps (e)-(h) in the ink jet headmanufacturing method in the first embodiment, which includes Steps(a)-(d) shown in FIG. 3.

FIG. 6 is a plan view of the back side of the substrate immediatelyafter the formation of the pilot holes in Step (f) shown in FIG. 5b.

FIG. 7 is a sectional view of the ink jet recording head chip, in thesecond embodiment of the present invention.

FIG. 8 is a sectional view of an ink jet recording head chip, which wasformed using a manufacturing method in accordance with the prior art,which does not form the pilot holes.

FIG. 9 is a sectional view of an ink jet recording head chip, thesubstrate of which has multiple common ink delivery channels which aredifferent in the position of the apex in their vertical cross sections.

FIG. 10a is a schematic drawing showing Steps (a)-(d) in the ink jetrecording head chip manufacturing method in the second embodiment of thepresent invention, which is for producing the ink jet recording headchip shown in FIG. 9.

FIG. 10b is a schematic drawing showing Steps (e)-(h) in the ink jetrecording head chip manufacturing method, which is for producing the inkjet recording head chip shown in FIG. 9.

FIG. 11 is a plan view of the back side of the precursor of the ink jetrecording head chip shown in FIG. 10a(b).

FIG. 12 is a plan view of the back side of the precursor of the ink jetrecording head chip, shown in FIG. 10b(f), which shows the pilot holesformed in Step (f) of the manufacturing method, shown in FIG. 10b.

FIG. 13 shows the sequence for forming the pilot holes.

FIG. 14 shows another example of a pilot hole.

FIG. 15 shows a further example of a pilot hole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be describedwith reference to the appended drawings.

The characteristic feature of the present invention which relates to themethod for processing the substrate for an ink jet recording head chipis that the substrate is anisotropically etched after blind pilot holesfor forming the common ink delivery channels (which hereafter will bereferred to simply as pilot holes) are formed by a laser. This featurewill be described in detail in the following preferred embodiments ofthe present invention.

Embodiment 1

FIG. 1 shows a part of the ink jet recording head in this embodiment ofthe present invention.

This ink jet recording head (liquid jetting head) has a siliconsubstrate 1, which has two rows of elements 3 for generating ink(liquid) jetting energy (which hereafter may be referred to simply asenergy generation elements). In each row, the energy generation elementsare aligned with a preset pitch. The silicon substrate 1 is covered witha layer of polyether-amide (unshown) as an adhesion enhancement layer.Also located on the silicon substrate 1 (adhesion enhancement layer) area photosensitive resin layer 9, which is the layer through which inkjetting holes 14 (liquid jetting hole) are formed. The ink jet holes 14are located above the energy generation elements 3, one for one. Thisphotosensitive layer 9 also serves as the top wall of each ink passagewhich leads from the common ink delivery channel 16 (liquid deliveryhole) to ink jetting hole 14. In terms of the direction perpendicular tothe abovementioned two rows of energy generation elements 3, the commonink delivery channel 16 (liquid delivery hole) formed by anisotropicallyetching the silicon substrate 1 is between the two rows of energygeneration elements 3. As the energy generated by each of the selectedgeneration elements 3 is applied to the body of ink in the correspondingink passage supplied from the common ink delivery channel 16, the ink isjetted out in the form of a droplet (droplets) from the correspondingink jetting hole 14, and adhere to recording medium, effecting therebyan image on recording medium.

This ink jet recording head is usable with various recordingapparatuses, for example, a printer, a copying machine, a facsimilemachine having a communication system, a wordprocessor having a printingportion, an industrial recording apparatus comprising a printer portionand various processing apparatuses, etc., which employ an ink jetrecording head (ink jet recording heads). This ink jet recording headcan record on various recording media, for example, paper, yarn, fiber,leather, metal, plastic glass, lumber, ceramic, etc. “Recording” in thefollowing description of the present invention means not only adherentlydepositing an image, such as a letter or a specific shape, which has ameaning, on recording medium, but also, adherently depositing ameaningless pattern on recording medium.

(Characteristic Features of Anisotropic Etching Method Which Uses PilotHoles)

According to the manufacturing method in this embodiment, the substrateis anisotropically etched after pilot holes 20 are formed in a presetpattern and to a preset depth by a laser. Therefore, this manufacturingmethod is more reliable as the method for forming the common inkdelivery channel 16, the cross-section of which is “< >”-shaped. Thismethod also makes it easier to form the common ink delivery channel 16,the cross section of which is “< >”-shaped. That the common ink deliverychannel 16 is “< >”-shaped means that, in terms of the width directionof the substrate, the width of the common ink delivery channel 16gradually increases, starting from its opening at the back surface ofthe substrate 1 toward a preset depth of the substrate 1, being largestat this depth, and then, gradually reduces toward its opening at thefront surface of the substrate 1. That is, in terms of thecross-sectional view of the common ink delivery channel 16, theabovementioned preset depth corresponds to the apex (peak) of the crosssection of the common ink delivery channel 16.

FIG. 2 is a sectional view of the precursor of the ink jet recordinghead chip, with which the manufacturing method in this embodiment iscompatible. FIG. 2 shows the cross section of the ink jet recording headchip, at a plane which coincides with a line A-A in FIG. 1 and isperpendicular to the substrate. Referring to FIG. 2, designated by areference numeral 2 is a sacrificial layer, and designated by areference numeral 4 is an etching stop layer (passivation layer).Designated by a reference numeral 1 is a substrate portion of the inkjet recording head chip, which is formed of silicon (hereinafter, thisportion may be referred to simply as substrate 1), and designated by areference numeral 8 is a mask formed on the back surface of the siliconsubstrate 1 to anisotropically etch the silicon substrate 1 from theback side. Designated by a reference numeral 20 is a pilot hole. Thesacrificial layer 2 is provided in an area 100 which is going to beformed with the ink delivery channel in the silicon substrate surface.The sacrificial layer 2 is effective in order to precisely define thearea of the ink delivery channel, but it is not inevitable in thepresent invention. The etching stop layer (passivation layer) is made ofa material having resistance properties against the material of theanisotropic etching. The etching stop layer 4 functions as a partitionwall or the like in the case that the surface of the silicon substrateis formed with elements and/or structures such as portions constitutingthe ink passage. When the sacrificial layer 2 and the etching stop layer4 are used alone or in combination, it will suffice if it or they areformed on the silicon substrate prior to the etching. In the step beforethe etching, the order of formations and the timing thereof are notlimited to specific nature, but may be as known by one skilled in theart. In this embodiment, at least two rows of pilot holes 20 are formedper common ink delivery channel 16, in terms of the width direction ofthe common ink delivery channel 16, in a back side of the ink jet headsubstrate, as will be evident from FIG. 2. It is preferable that thepilot holes 20 are formed in two straight rows which are symmetricallypositioned with reference to the center line (parallel to lengthwisedirection of common ink delivery channel) of the common ink deliverychannel 16, in terms of the width direction (which is perpendicular tosurface of paper on which FIG. 2 is drawn) of the common ink deliverychannel 16 (FIG. 5). Incidentally, in this disclosed embodiment, thepilot holes 20 are formed in two straight rows.

FIG. 3 schematically shows the sequential steps in the process foranisotropically etching the silicon substrate 1 which has the pilotholes 20 formed in advance, as shown in FIG. 2. In the followingexamples, the use is made with a sacrificial layer 2 and a passivationlayer 4.

First, the substrate 1 is etched from its back side (bottom side). Thus,not only does the etching start at the deepest end of each pilot hole 20and progress toward the top surface of the substrate 1, but also, theetching starts across the entirety of the internal surface of the pilothole 20 and progresses in the direction (left-and-right direction ofdrawing) perpendicular to the thickness direction of the substrate 1. Asa result, each pilot hole 20 grows into a cavity (precursor of commonink delivery channel), the top portion of which has <111> surfaces 21aand 21b, which are slanted so that the width of the cavity graduallyreduces toward the top surface, and the bottom portion of which has a<111> surface 22, which is slanted so that the width of the cavitygradually increases toward the top surface (FIG. 3(a)).

As the etching progresses further, the <111> surface 21b of one of thepilot holes 20 comes into contact with the <111> surface 21b of theother pilot hole 20, effecting an apex, and then, the etching begins toprogress from this apex toward the top surface of the substrate 1.Further, the <111> surface 21a, or the outward surface, with referenceto the center of the substrate 1, intersects with the <111> surface 22,which extends from the bottom surface of the substrate 1. As a result,the apparent growth of the cavity in the direction perpendicular to thethickness direction of the substrate 1 stops (FIG. 3(d)). It is addedthat the etching can be finished without the sacrificial layer.

As the etching progresses further, a <100> surface 23 is formed betweenthe two pilot holes 20 (FIG. 3(c)). The progression of the etchingprocess causes this <100> surface 23 to shift toward the top surface ofthe substrate 1. Eventually, the <100> surface 23 reaches thesacrificial layer 2, when the anisotropic etching is ended (FIG. 3(d)).

In the method, such as the above described one, for forming the commonink delivery channel 16, the final position of each <111> surface 21awhich is inclined so that the width of the common ink delivery channel16 gradually reduces toward the top surface of the substrate 1, isdetermined by the position of the pilot hole 20. Further, the finalposition of the <111> surface 22 which grows from the bottom surface ofthe bottom surface of the substrate 1 is determined by the position ofeach of the holes of the mask 8 which is placed on the bottom surface ofthe substrate 1.

FIG. 4 is a sectional view of the precursor of an ink jet recording headchip, the substrate of which had only a single row of the pilot holes20, which was parallel to the lengthwise direction of the common inkdelivery channel 16. In the case of the precursor shown in FIG. 4, theapparent progression of the anisotropic etching process sometimes stopsat the apex which is formed by two <111> surfaces 61a and 61b andcorresponds in position to the inward end of the pilot hole 20, andtherefore, it is difficult to expose the sacrificial layer 2 from thebottom side of the substrate 1. Moreover, if an attempt is made to forma pilot hole (20) long enough to reach the sacrificial layer 2, it ispossible that the beam of laser light might penetrate the sacrificiallayer 2 and etching stopping layer 4. Further, if there are functionallayers, such as a wiring layer, which were formed in advance, on the topsurface of the substrate 1, the beam of laser light may damage thefunctional layers after penetrating these two layers 2 and 4. Moreover,if there are ink passages, which were formed in advance, on the topsurface of the substrate 1, it is possible that the beam of laser lightwill damage the ink passages. Therefore, it is difficult to preciselyform the common ink delivery channel 16 which has the desired shape anddimension, by forming only a single row of pilot holes 20.

Referring again to FIG. 2, a character L stands for the width of thesacrificial layer 2 (distance between two ends of closest surface ofsacrificial layer 2 to bottom surface of silicon substrate 1), and acharacter T stands for the thickness of the silicon substrate 1. Acharacter X stands for the distance from the center of the sacrificiallayer 2 to the center of the adjacent pilot hole 20, and a character Dstands for the depth of the pilot hole 20. Further, a character Y standsfor the width of the opening of the hole in the bottom surface mask 8.In an example using the sacrificial layer 2, the sacrificial layer 2 isprovided in the area which is to be bored for the ink delivery channelin the silicon substrate surface, and therefore, the centers and ends ofthe sacrificial layer 2 and the area are aligned with each other.

In order to expose the sacrificial layer 2 by anisotropically etchingthe substrate 1 from the bottom side of the substrate 1 during the abovedescribed progression of the ink jet head manufacturing process, thedepth D of each pilot hole 20 is desired to fall within the followingrange which satisfies the following expression:T−(X−L/2)×tan 54.7°≧D≧T−X×tan 54.7°  (1).

Further, in order to form the common ink delivery channel 16 describedabove, the cross section of which is “< >”-shaped, the width Y of theopening of the hole in the bottom surface mask 8 is desired to satisfythe following expression:(T/tan 54.7°)×2+L≧Y  (2).

On the other hand, if the width Y of the opening of the hole in thebottom surface mask 8 is greater than (T/tan 54.7°)×2+L, a common inkdelivery channel, which has only two <111> surfaces (lateral surfaces),the distance between which is greatest at the bottom of the siliconsubstrate 1 and gradually decreases toward the top surface of thesubstrate 1, is formed.

As described above, the manufacturing method, in this embodiment, for anink jet recording head chip makes it possible to form various kinds ofcommon ink delivery channels (16), which are different in terms of theshape of their cross sections, by changing the pattern in which thepilot holes 20 are arranged, the depth of each pilot hole 20, and/or thewidth of the opening of the hole of the bottom surface mask 8, asnecessary. That is, not only can the ink jet recording head chipmanufacturing method in this embodiment make it possible to form acommon ink delivery channel (16), which is relatively wide at the bottomsurface of the substrate 1, and the apex of each side wall of which islocated close to the bottom surface of the substrate 1, but also, acommon ink delivery channel (16), which is relatively narrow at thebottom surface of the substrate 1, and the apex of each side wall ofwhich is located close to the middle of the substrate 1 in terms of thethickness direction of the substrate 1.

In the manufacturing method, in this embodiment, for the ink jetrecording head chip, the pilot holes 20 for forming the common inkdelivery channel 16 with the “< >”-shaped cross section are formed withthe use of a laser. The usage of a laser makes it possible to preciselyprocess preset points (portions) of the substrate 1 at a high speed.Further, it does not require the substrate 1 to be processed (forexample, it does not require mask or the like to be formed on substrate1) before it is processed by a laser. Therefore, it makes it possible toreduce the number of steps necessary for forming the common ink deliverychannel 16, the cross section of which is “< >”-shaped.

Further, the liquid etchant enters the pilot holes 20 in the substrate1, reducing thereby the length of time necessary for forming the commonink delivery channel 16, compared to an ink jet recording head chipmanufacturing method which does not form pilot holes for the common inkdelivery channels.

Regarding the step for forming the pilot holes 20, changing theconditions under which the pilot holes 20 are formed, based on thethickness of the silicon substrate, which was measured in advance, makesit possible to more reliably form the common ink delivery channels 16.

Normally, silicon wafers used as the material for the substrate 1 forthe ink jet recording head chip are not the same in thickness; they varyin thickness within a range of roughly 30-50 μm. That is, the thicknessT (in Expression (1)) of the silicon substrate 1 (silicon wafer) variesin the range of 30-50 μm, which reduces the range of D, reducing therebythe margin for this step. However, by measuring in advance the thicknessof the silicon substrate 1 (silicon wafer), it is possible to reduce theapparent effects of the deviation in the thickness T of the siliconsubstrate 1 (silicon wafer).

(Method for Feeding Back Measured Thickness of Substrate (SiliconWafer))

FIG. 13 shows the sequence for forming the pilot holes. First, thethickness of the substrate 1 (silicon wafer) is measured with the use ofa silicon substrate (wafer) thickness measuring device. Then, based onthe measured thickness of the substrate 1 (silicon wafer), the optimalconditions for processing the substrate 1 (silicon wafer) with the useof a laser-based processing apparatus are selected. Then, the pilotholes 20 are formed with the laser-based processing apparatus, under theselected (optimal) conditions.

Once the nozzle formation layer is formed on the top surface of thesubstrate 1 (silicon wafer), it is impossible to directly measure thethickness of the substrate 1 (silicon wafer) with the use of an ordinarythickness measuring device, that is, a silicon substrate (wafer)thickness measuring device of the reflection type. Therefore, when asilicon substrate (wafer) thickness measuring device of the reflectiontype is used for measuring the thickness of the substrate 1 (siliconwafer), the thickness must be measured before the nozzle formation layeris formed (this process will be described later, referring to FIG. 5a,(a)). There are various manufacturing steps between the measurement ofthe thickness of the substrate 1 (silicon wafer) and the formation ofthe pilot holes 20, making it difficult to match the values obtained bymeasuring the thicknesses of a substantial number of substrates 1(silicon wafers), with the corresponding substrates 1 (silicon wafer).Therefore, it is desired to provide a laser-based processing apparatuswith a function of identifying (reading) the identification number ofeach substrate 1 (silicon wafer) so that the optimal conditions for theformation of the pilot holes 20 can be selected for the substrate 1(silicon wafer), after it is confirmed that a specific value among manyvalues obtained by measuring the thicknesses of a substantial number ofsubstrates 1 (silicon wafers) matches the substrate 1 (silicon wafer)which is going to be used next as the material for the manufacturing ofthe ink jet recording head chip.

On the other hand, when a silicon substrate (wafer) thickness measuringdevice which uses near infrared rays is used as the device for measuringthe thickness of the substrate 1 (silicon wafer), the thickness of thesubstrate 1 (silicon wafer) can be directly measured even if there is anozzle formation layer on the top surface of the substrate 1 (siliconwafer). That is, in this case, the thickness of the substrate 1 (siliconwafer) can be measured after the formation of the nozzle formation layer(this process will be described later, referring to FIG. 5b, (f)). Thus,it is possible to place a silicon wafer thickness measuring device whichuses near infrared rays, in a laser-based processing apparatus so thatthe thickness of the substrate 1 (silicon wafer) can be measuredimmediately before the formation of the pilot holes 20.

(Method for Changing Conditions)

The conditions for processing the substrate 1 with the use of a laser toform the pilot holes 20 are to be changed, as necessary, based on thethickness of the substrate 1 (silicon wafer) measured as describedabove. The conditions which are changeable are the following two.

One is the depth D of each pilot hole 20 (which is to be changed basedon the thickness of the substrate 1. If the thickness of the substrate 1is greater than the normal one, the depth D of the pilot hole 20 is tobe increased, whereas the thickness of the substrate 1 is less than thenormal one, the depth of the pilot hole 20 is to be reduced. The depth Dcan be changed by adjusting laser output, and/or laser shot count.

The other condition is the distance X, or the distance between thecenters of the area to be bored for the ink delivery channel in thesubstrate surface (the sacrificial layer 2 when the sacrificial layer isprovided) and pilot hole 20 (which is to be changed based on thicknessof substrate 1). If the thickness of the substrate 1 is greater than thenormal one, the distance X is to be increased, whereas the thickness ofthe substrate 1 is less than the normal one, the distance X is to bereduced. By changing the distance X, the ink jet recording head chipswhich will be yielded from one silicon wafer can be made the same asthose from another silicon wafer, in terms of the width of the topopening of the common ink delivery channel 16 (width of top end ofcavity when cavity grown to sacrificial layer).

Referring to FIGS. 5A and 5B, the process for manufacturing an ink jetrecording head using the above described ink jet recording head chipmanufacturing method will be described. Incidentally, the preferredembodiments of the present invention, which were described so far andwill be described hereafter, are not intended to limit the presentinvention in scope. That is, the present invention is also applicable toother technologies which are compatible with the gist of the presentinvention stated in the claim section of this application.

FIGS. 5A(A)-5A(D) and 5B(E)-5B(H) are sectional views of the ink jetrecording head chip in the various stages completion, at a line A-A inFIG. 1.

On the top surface of the substrate 1 shown in FIG. 5a, (a), there aremultiple ink jetting energy generation elements 3, such as heatgenerating resistors, for generating the energy for jetting ink. Theentirety of the bottom surface of the substrate 1 is covered with asilicon dioxide film 6. Also the sacrificial layer 2 is provided on thetop surface of the substrate 1. The sacrificial layer 2 is dissolvedaway with alkaline solvent when forming the common ink delivery channel16. The wiring for the energy generation elements 3 and thesemiconductors for driving the heaters (energy generating elements 3)are not shown. The sacrificial layer 2 is formed of such a substance aspolysilicon, aluminum (which can be quickly etched), aluminum-silicon,aluminum-copper, and aluminum-silicon-copper, which can be etched withalkaline solvent, although the selection does not need to be limited tothese examples. That is, any substance which is greater in the speed atwhich it can be etched with alkaline solvent, than silicon may beselected. The etching stop layer 4 must be capable of preventing thesubstrate 1 from being further etched by alkaline solvent, once thesacrificial layer 2 is exposed during the anisotropic etching of thesubstrate 1. It is preferred that the etching stop layer 4 is formed ofsilicon dioxide, which is also used as the material for the heat storagelayer placed on the bottom side of the heater 3, silicon nitride, whichis also used as the material for the protective layer placed on theenergy generating element 3, or the like.

Referring to FIG. 5a, (b), polyether-amide resins (7) and (8) are coatedon the top and bottom surfaces of the substrate 1, respectively, and arehardened by baking. Then, in order to pattern the polyether-amide resinlayer 7, the positive resist (unshown) is spin coated on the top surfaceof the resin layer 7, is exposed in a preset pattern, and is developed.Then, the polyether-amide resin layer 7 is etched in the preset patternby dry etching or the like method. Then, the positive resist is removed.Similarly, in order to pattern the polyether-amide resin layer 8,positive resist (unshown) is coated on the polyether-amide resin layer 8on the bottom surface of the substrate 1, is exposed in a presetpattern, and is developed. Then, the polyether-amide resin layer 8 isetched or the like method in the preset pattern. Then, the positiveresist is removed.

Referring to FIG. 5a, (c), positive resist 10 which is to be removed toform an ink passage is placed in the pattern of the ink passage.

Referring to FIG. 5a, (d), photosensitive resin as the material forforming nozzles is coated by spin coating or the like method on the topside of the substrate 1 in a manner to cover the positive resist 10.Then, a water repellant dry film 13 is placed on the photosensitiveresin layer 12 by lamination or the like method. Then, thephotosensitive resin layer 12 is patterned. That is, it is exposed in apreset pattern, with the use of ultraviolet rays, deep ultraviolet rays,or the like, and is developed, forming an ink jetting hole 14 throughthe photosensitive resin layer 12.

Referring to FIG. 5b, (e), the top side of the substrate 1, on which thepositive resist 10, photosensitive resin layer 12, etc., are present,and the lateral sides of the substrate 1, are coated with a protectivelayer 15 by spin coating or the like method.

Referring to FIG. 5b, (f), the pilot holes 20 are formed with the use ofa laser, from the bottom side of the substrate 1 toward the top side. Inthis step, two straight rows of pilot holes 20 are formed per common inkdelivery channel 16 so that the two rows are symmetrically positionedwith reference to the center of the sacrificial layer 2. As the meansfor forming the pilot holes 20, a beam of frequency-tripled (THG: 355 nmin wavelength) laser light emitted by a YAG laser is used. The power andfrequency of the laser was set to optimum values. In this embodiment,the diameter of the pilot hole 20 is roughly 40 μm. The diameter of thepilot hole 20 is desired to be in a range of roughly 5-100 μm. If it isexcessively small, it is difficult for the etchant to enter the pilothole 20 during the subsequent step in which the substrate 1 isanisotropically etched. On the other hand, if the diameter of the pilothole 20 is excessively large, it takes an excessive length of time toform the pilot hole 20 with the preset depth. Incidentally, if it isnecessary to increase the diameter of the pilot hole 20, the pitch withwhich the pilot holes 20 are formed must be set so that the adjacent twopilot holes 20 do not overlap.

FIG. 6 is a plan view of the bottom side of the substrate 1 after theformation of the pilot holes 20 in the step shown in FIG. 5b, (f). Thepolyether-amide layer 8 (bottom surface mask) on the bottom surface ofthe substrate 1 has holes 28, the positions of which correspond to thoseof the strips of sacrificial layer 2 (contoured by dotted line in FIG.6), one for one, on the top surface of the substrate 1. These hole 28are formed in the step shown in FIG. 5a, (b), and the polyetheramideresin layer 8 functions as the mask used for anisotropically etching thesubstrate 1. The thickness of the substrate 1 (silicon wafer) measuredat this point in the manufacturing process, with the use of theabovementioned silicon wafer thickness measuring device which uses nearinfrared rays was 600 μm. The dimension of the sacrificial layer 2 interms of its width direction was 150 μm. The pitch of the multiplecommon ink delivery channels 16 was 1,500 μm. The distance X, or thedistance between the centers of the sacrificial layer 2 and pilot hole20, in terms of the width direction of the substrate 1, was set to 100μm. Then, the pilot holes 20 were formed, with the number of pulses oflaser light set according to these measurements, and the Expression (1),so that the depth of the pilot holes 20 will be in a range of 490-530μm. The pilot holes 20 were formed in the portions of the substrate,which corresponds in position to the holes 28. In terms of the widthdirection of the substrate 1, the pitch of the holes 28 was set to 200μm, and in terms of the lengthwise direction of the substrate 1, thepitch of the holes 28 was set to 100 μm.

In this embodiment, the dimension of the hole 28 in the width directionof the substrate 1 is 400 μm. The width of the sacrificial layer 2 inthe width direction of the substrate 1 is 150 μm. The depths of thepilot holes 20 measured, in terms of vertical cross section, after theforming of the pilot holes 20 using a laser was in a range of 420-460μm. The thickness of the substrate 1 measured with the use of theabovementioned silicon wafer thickness measuring device which uses nearinfrared rays at this point in the manufacturing process was 600 μm.Thus, from these measurements and Expression (1), the distance X, or thedistance between the centers of the sacrificial layer 2 and pilot hole20, was set to 150 μm. Then, the pilot holes 20 were formed. That is,multiple pilot holes 20 were formed so that their pitch in terms of thewidth direction of the hole 28 was 300 μm, and their pitch in terms ofthe lengthwise direction of the hole 28 was 150 μm.

As regards the formed pilot hole, there are other examples shown inFIGS. 14 and 15. In FIG. 14 example, the interval of the pilot holes inone of the two rows formed along the longitudinal direction of theopening of the masking layer, is smaller than that in the other row.With such a structure, the anisotropic etching in the large intervalpart becomes closer to that in the smaller interval part. As a result,the number of the pilot holes can be substantially decreased, andtherefore, the productivity is improved. In FIG. 15 example, the pilotholes arranged in two rows in the longitudinal direction of the openingin the masking layer are in connection with are partly (FIG. 15(a)) orentirely (FIG. 15(b)) with the pilot holes in the same row into achannel shape. This structure can be provided by continuous scanningwith a laser beam. This example is advantageous in that the depths ofthe unpenetrated holes from the back side of the substrate are uniformover the unpenetrated holes.

In this embodiment, a beam of frequency-tripled (THG: 355 nm inwavelength) laser light emitted by a YAG laser was used to process thesubstrate 1 to form the pilot holes 20. However, the beam of laser lightused for processing the substrate 1 does not need to be limited to theabovementioned one, as long as the wavelength of the laser light issuitable for forming holes through silicon, or the material for thesubstrate 1. For example, a beam of frequency-doubled (SHG: 532 nm inwavelength) laser light emitted by a YAG laser, which is as high in theabsorbency by silicon as THG, may be used form the pilot holes 20.

Referring to FIG. 5b, (c), the silicon dioxide film 6 in the hole 28(FIG. 6) on the bottom side of the substrate 1 is removed to expose thesurface of the silicon substrate 1, at which the anisotropic etching ofthe substrate 1 is started. Then, the formation of the common inkdelivery channel 16 is started. More specifically, the portions of thesilicon dioxide film 6 on the bottom surface of the substrate 1, whichare exposed through the holes 28, are removed, with the polyether-amideresin layer 8 used as a mask. Thereafter, the common ink deliverychannels 16 which will reach sacrificial layer 2, one for one, areformed by etching the silicon substrate 1 from the bottom side, usingTHAH TMAH (tetramethyl ammonium hydroxide) as anisotropic etchant. Inthis etching step, the etching front advances through the stagesdescribed with reference to FIG. 3, and the resultant <111> surfaces,the angles of which are 54.7°, reach the sacrificial layer 2. Then, thesacrificial layer 2 is isotropically etched by the etching fluid,effecting the top portion of the common ink delivery channel 16, whichreflects the shape of the sacrificial layer 2. The cross section of thecommon ink delivery channel 16 at the line A-A in FIG. 1, which iscontoured by the <111> surfaces, is “< >”-shaped.

Lastly, referring to FIG. 5b, (h), the portion of the etching stop layer4, which is covering the top opening of the common ink delivery channel16, is removed by dry etching. Then, the polyether-amide layer 8 andprotective layer 15 are removed. Further, the positive resist layer 10is dissolved out through the ink jetting hole 14 and common ink deliverychannel 16 to effect the ink passages and bubble generation chambers.

Each ink jet recording head chip, or the substrate 1 having the nozzleportion, is completed through the above described manufacturing steps.Then, the silicon wafer is separated into individual ink jet recordinghead chips with the use of a dicing saw or the like. Then, wiring fordriving the ink jetting energy generating element 3 is attached to eachchip, and an ink container for an ink jet recording head chip isconnected to each chip, completing an ink jet recording head.

Incidentally, in this embodiment, a silicon wafer which is 600 μm inthickness was used as the material for the substrate 1 for the ink jetrecording head chip. However, the present invention is also applicableto an ink jet recording head chip manufacturing method which uses asilicon wafer or the like, which is thinner or thicker than the siliconwafer used in this embodiment. When such a material is used as thesubstrate, the depth of the pilot hole 20 and the dimension of the hole28 should be changed to the values which satisfy Expressions (1) and(2).

Further, the common ink delivery channel 16 can be formed by carryingout multiple times the sequential steps shown in FIGS. 5B(F)-5B(H),instead of using the common ink delivery channel forming method in thisembodiment. More specifically, a single row of pilot holes 20 which donot reach the sacrificial layer, are formed, and the substrate 1 isanisotropically etched using this row of pilot holes 20. Then, the nextrow of pilot holes 20 is formed next to the groove (cavity) formed usingthe first row of pilot holes, and then, the substrate 1 isanisotropically etched to complete the common ink delivery channel 16.In this case, when forming the pilot hole 20 so that it reaches thesacrificial layer, Expression (1) must be satisfied.

Embodiment 2

FIG. 7 is a sectional view of the ink jet recording head chip in thesecond embodiment of the present invention.

The ink jet recording head chip in this embodiment is provided withmultiple common ink delivery channels, which were formed in parallelwith the use of the manufacturing method in the first embodimentdescribed above. Thus, each common ink delivery channel 16 of the inkjet recording head chip in this embodiment also has the “< >”-shapedcross section.

FIG. 8 is a sectional view of an ink jet recording head chip formed withthe use of an ink jet head manufacturing method in accordance with theprior art, which does not use pilot holes to form the common inkdelivery channels As will be evident from the comparison between FIGS. 7and 8, the ink jet recording head chip manufacturing method in thisembodiment used for forming the ink jet recording head chip shown inFIG. 7, makes it possible to form the common ink delivery channel 16,the width of which on the bottom side is smaller than that of the commonink delivery channel 16, shown in FIG. 8, formed with the use of an inkjet recording head chip manufacturing method in accordance with theprior art. Thus, the ink jet recording head chip manufacturing method inthis embodiment can produce an ink jet recording head chip, in which thedistance between the adjacent two common ink delivery channels 16 issmaller than that in an ink jet recording head chip formed with the useof the ink jet recording head chip manufacturing method in accordancewith the prior art. Therefore, it can produce an ink jet recording headchip, which is smaller than the one produced with the use of the ink jetmanufacturing method in accordance with the prior art. Further, thecommon ink delivery channels 16 in this embodiment have the “< >”-shapedcross section, making it possible to produce an ink jet recording headchip, in which the width of the surface area 50, by which the adjacenttwo common ink delivery channels 16, which are different in the color ofthe inks therein, is separated, is much wider, being therefore capableof better preventing the inks in the adjacent common ink deliverychannels 16 from mixing, than that in an ink jet recording head chipproduced with the use of an ink jet head manufacturing method inaccordance with the prior art.

Also in the case of the ink jet recording head chip manufacturing methodin this embodiment, the pattern in which the pilot holes 20 are formed,the depth of each pilot hole 20, the width of each hole of the bottomsurface mask 8, may be changed to form various kinds of common inkdelivery channels 16 having the “< >”-shaped cross section, for example,a common ink delivery channel 16, the bottom opening of which is greaterthan the top opening thereof, and the apex of its “< >”-shaped crosssection is closer to the bottom surface of the substrate 1, as well as,a common ink delivery channel 16, the bottom opening of which is smallerthan the top opening thereof, and the apex of its “< >”-shaped crosssection is near the middle of the substrate 1 in terms of the thicknessdirection of the substrate 1.

As described above, in the case of an ink jet recording head chip havingmultiple common ink delivery channels 16 which are in the substrate 1 ofthe chip, the position (in terms of thickness direction of substrate 1)of the apex of the “< >”-shaped cross section of each common inkdelivery channel 16 can be changed by satisfying the inequalities:Y1>Y2, or Y1<Y2, in which Y1 and Y2 (FIG. 9) are the widths of the holesof the bottom surface mask 8, which correspond to the bottom openings ofthe adjacent two common ink delivery channels 16, and can be obtainedfrom the abovementioned Expression (2):(T/tan 54.7°)×2+L≧Y   (2).An ink jet recording head chip, which has multiple common ink deliverychannels 16 arranged in parallel can be further reduced in size bydifferentiating the adjacent two common ink delivery channels 16 in theposition of the apexes of their “< >”-shaped cross sections. FIG. 9 is across sectional view of an ink jet recording head chip structured asdescribed above. As will be evident from FIG. 9, by differentiating theadjacent two common ink delivery channels 16 in the position of theapexes of their “< >”-shaped cross sections, the two common ink deliverychannels 16 can be placed closer so that the apexes of the “< >”-shapedcross sections of the two common ink delivery channels 16 virtuallyoverlap, making it possible to further reduce in size an ink jetrecording head chip, compared to an ink jet recording head chipstructured as shown in FIG. 7. In the case of the structural arrangementshown in FIG. 9, the distance between the apexes of the “< >”-shapedcross sections of the adjacent two common ink delivery channels 16 isgreater than that shown in FIG. 7. Therefore, the portion 50 of thechip, which separates the adjacent two common ink delivery channels 16different in the color of the ink therein, can be increased in strength.

Next, referring to FIGS. 10A and 10B, the manufacturing method for theink jet recording head which includes the ink jet recording head chipshown in FIG. 9 will be described. Incidentally, the preferredembodiments of the present invention are not intended to limit thepresent invention in scope. That is, the present invention is alsoapplicable to the technologies other than those in the preferredembodiment, as long as the technologies are compatible with the conceptof the present invention stated in the claim section of this patentapplication.

The ink jet recording head chip, which is shown in FIG. 10a, (a), isprovided with multiple ink jetting energy generation elements 3, such asheat generating resistors, which are on the top surface of the substrate1. The entirety of the bottom surface of the substrate 1 is covered witha silicon dioxide film 6. There are also multiple strips of sacrificiallayer 2 on the top surface of the substrate 1. Each strip of sacrificiallayer 2 is dissolved away with alkaline solvent when forming the commonink delivery channel 16. The wiring for the energy generation elements 3and the semiconductors for driving the heaters are not shown. Thesacrificial layer 2 is formed of such a substance as polysilicon,aluminum (which can be quickly etched), aluminum-silicon,aluminum-copper, and aluminum-silicon-copper, which can be etched withalkaline solvent. The etching stop layer 4 must be capable of preventingthe substrate 1 from being further etched by alkaline solvent, once thesacrificial layer 2 is exposed during the anisotropic etching of thesubstrate 1. It is preferred that the etching stop layer 4 is formed ofsilicon dioxide, which is also used as the material for the heat storagelayer placed on the back surface side of the heater 3, silicon nitride,which is also used as the material for the protective layer placed onthe energy generating element 3, or the like.

Next, referring to FIG. 10a, (b), polyether-amide resins (7) and (8) arecoated on the top and bottom sides of the substrate 1, respectively, andare hardened by baking. Then, in order to pattern the polyether-amideresin layer 7, the positive resist (unshown) is spin coated on the topsurface of the polyether-amide resin layer 7, is exposed in a presetpattern, and is developed. Then, the polyether-amide resin layer 7 isetched in the preset pattern by dry etching or the like method. Then,the positive resist is removed. Similarly, in order to pattern thepolyether-amide resin layer 8, positive resist (unshown) is coated onthe polyether-amide resin layer 8 on the bottom surface of the substrate1, is exposed in a preset pattern, and is developed. Then, thepolyether-amide resin layer 8 is etched by dry etching or the likemethod in the preset pattern. Then, the positive resist is removed.

The width of the opening of the hole in the bottom surface mask 8patterned on the bottom surface of the substrate 1 equals the width ofthe bottom opening of the common ink delivery channel 16. Therefore, thewidth of the opening of the hole in the bottom surface mask 8 is set sothat it equals the intended width of the bottom opening of the commonink delivery channel 16. FIG. 11 is a bottom plan view of the precursorof the ink jet recording head chip, which is shown in FIG. 10a, (b). Inthis embodiment, the measurement Y1 of the opening of the larger hole inthe bottom surface mask 8, in terms of the width direction of thesubstrate 1, is 800 μm, and the measurement Y2 of the opening of thesmaller hole in the bottom surface mask 8, in terms of the widthdirection of the substrate 1, is 400 μm.

Next, referring to FIG. 10a, (c), positive resist 10 which is to beremoved to form an ink passage is placed in the pattern of the inkpassage.

Referring to FIG. 10a, (d), photosensitive resin 12 as the material forforming nozzles is coated by spin coating or the like method on the topside of the substrate 1 in a manner to cover the positive resist 10.Then, a water repellant dry film 13 is placed on the photosensitiveresin layer 12 by lamination or the like method. Then, thephotosensitive resin layer 12 is patterned. That is, it is exposed in apreset pattern, with the use of ultraviolet rays, deep ultraviolet rays,or the like, and is developed, forming an ink jetting holes 14 throughthe photosensitive resin layer 12.

Referring to FIG. 10b, (e), the top side of the substrate 1, on whichthe positive resist 10, photosensitive resin layer 12, etc., arepresent, and the lateral surfaces of the substrate 1, are coated with aprotective layer 15 by spin coating or the like method.

Referring to FIG. 10b, (f), the pilot holes 20 are formed with the useof a laser, from the bottom side of the substrate 1 toward the top side.In this step, two straight rows of pilot holes 20 are formed per commonink delivery channel 16 so that the two rows are symmetricallypositioned with reference to the center of the sacrificial layer 2. Asthe means for forming the pilot holes 20, a beam of frequency-tripled(THG: 355 nm in wavelength) laser light emitted by a YAG laser. Thepower and frequency of the laser was set to optimum values. In thisembodiment, the diameter of the pilot hole 20 is roughly 40 μm. Thediameter of the pilot hole 20 is desired to be in a range of roughly5-100 μm. If it is excessively small, it is difficult for the etchant toenter the pilot hole 20 during the subsequent step in which thesubstrate 1 is anisotropically etched. On the other hand, if thediameter of the pilot hole 20 is excessively large, it takes anexcessive length of time to form the pilot hole 20 with the desireddepth. Incidentally, if it is necessary to increase the diameter of thepilot hole 20, the pitch with which the pilot holes 20 are formed mustbe set so that the adjacent two pilot holes 20 do not overlap.Incidentally, an ink jet recording head chip, the multiple common inkdelivery channels 16 of which are the same in the width of their topopenings, can be produced by keeping constant the conditions under whichthe substrate 1 is processed to form the pilot holes 20.

FIG. 12 is a plan view of the bottom side of the substrate 1 after theformation of the pilot holes 20 in the step shown in FIG. 10b, (f). Thepolyether-amide layer 8 (bottom surface mask) on the bottom surface ofthe substrate 1 has the holes 28, the positions of which correspond tothose of the intended ink opening position (the sacrificial layers 2 inthe case of the provision of the sacrificial layer)(contoured by dottedlines in FIG. 12) on the top surface of the substrate 1. These holes 28are formed in the step shown in FIG. 10a, (b), and the polyether-amidelayer 8 functions as the mask used for anisotropically etching thesubstrate 1.

Incidentally, in this embodiment, the pilot holes 20 were formed withthe use of the frequency-tripled (THG: 355 nm in wavelength) beam oflaser light emitted by a YAG laser. However, the selection of the beamof laser light used for processing the substrate 1 to form the pilotholes 20 does not need to be limited to the one used in this embodiment,as long as the selected laser light can form a hole through silicon, orthe material for the substrate 1. For example, a beam offrequency-doubled (SHG: 532 nm in wavelength) laser light emitted by aYAG laser, which is as high in the absorbency by silicon as THG, may beused to form the pilot holes 20.

Next, referring to FIG. 10b, (g), the portions of the silicon dioxidefilm 6 in the holes 28 (FIG. 12) on the bottom surface of the substrate1 are removed to expose the surface of the silicon substrate 1, at whichthe anisotropic etching of the substrate 1 is to be started. Then, theformation of the common ink delivery channels 16 is started. Morespecifically, the portions of the silicon dioxide film 6 on the bottomsurface of the substrate 1, which are exposed through the holes 28, areremoved, with the polyether-amide resin layer 8 used as a mask.Thereafter, the common ink delivery channels 16 are formed by etchingthe silicon substrate 1 from the bottom side, using THAH TMAH(tetramethyl ammonium hydroxide) as anisotropic etchant so that thecommon ink delivery channels 16 reach sacrificial layers 2, one for one.In this etching step, the etching of the substrate 1 starts at the endof each pilot hole 20, and as the etching continues, and the resultant<111> surfaces, the angles of which relative to the bottom surface ofthe substrate 1 are 54.7° reach the sacrificial layer 2. Then, each ofthe sacrificial layers 2 is isotropically etched by the etching fluid,effecting the top portion of the common ink delivery channel 16, whichreflects the shape of the sacrificial layer 2. Each common ink deliverychannel 16 is formed so that its cross section, which is contoured bythe <111> surfaces, is “< >”-shaped. In this embodiment, the positionsof the apexes of the “< >”-shaped cross sections of the adjacent twocommon ink delivery channels 16 are separated by roughly 140 μm in termsof the thickness direction of the substrate 1.

Lastly, referring to FIG. 10b, (h), the portion of the etching stoplayer 4, which is covering the top opening of the common ink deliverychannel 16, is removed by dry etching. Then, the polyether-amide layer 8and protective layer 15 are removed. Further, the positive resist layer10 is dissolved out through the ink jetting hole 14 and common inkdelivery channel 16 to effect the ink passages and bubble generationchambers.

The precursor of the ink jet recording head chip, or the substrate 1having the nozzle portion, is completed through the above describedmanufacturing steps. Then, the silicon wafer is separated with the useof a dicing saw or the like, into individual ink jet recording headchips. Then, wiring for driving the ink jetting energy generatingelement 3 is attached to each ink jet recording head chip, and an inkcontainer for an ink jet recording head chip is connected to each chip,completing an ink jet recording head.

Incidentally, in this embodiment, a silicon wafer which is 600 μm inthickness was used to manufacture the ink jet recording head chips.However, the present invention is also applicable to an ink jetrecording head chip manufacturing method which uses a silicon wafer orthe like, which is thinner or thicker than the silicon wafer used inthis embodiment. When such a silicon wafer or the like is used, thedepth of the pilot hole 20 and the dimension of the hole 28 should bechanged to the values which satisfy Expressions (1) and (2).

Described above is an example of the common ink delivery channel formingmethod, in which the position (in terms of thickness direction ofsubstrate) of the apexes of the “< >”-shaped cross section of the commonink delivery channel, is changed by changing the dimension (in terms ofwidth direction of substrate) of the opening of the hole in the bottomsurface mask 8.

While the invention has been described with reference to the structuresdisclosed herein, it is not confined to the details set forth, and thisapplication is intended to cover such modifications or changes as maycome within the purposes of the improvements or the scope of thefollowing claims.

This application claims priority from Japanese Patent Application No.061166/2006 filed Mar. 7, 2006 which are hereby incorporated byreference.

What is claimed is:
 1. A manufacturing method for a substrate for an inkjet head including an energy generating element for generating energyused to eject ink and an ink supply port for supplying the element withink, said method comprising: providing a substrate having the element, asacrificial layer of material having an etching speed which is higherthan that of silicon on an area where said ink supply port is going tobe formed at a side of a first surface, and an etching mask layer havingan opening at a position corresponding to the ink supply port on asecond surface which is a back surface of opposite the first surface ofsaid substrate and which has a plane direction <100>; forming recessesin the first surface in substrate in an area of the substrate exposed bythe opening at the second surface in first and second rows extending ina longitudinal direction of said opening in sides of a center of saidopening with respect to a widthwise direction of said opening, whereinsaid recesses in the first and second rows include a recess satisfyingT−(X−L/2)×tan 54.7°≧D≧T−X×tan 54.7° where L (μm) is a length of thesacrificial layer in a widthwise direction of the sacrificial layer, T(μm) is a thickness of said substrate, X (μm) is a distance from acenter of said sacrificial layer in a the widthwise direction to centersof said recesses, and D is a depth of said recesses; and forming saidink supply port by crystal anisotropic etching of said substrate throughsaid opening.
 2. The method according to claim 1, wherein said recessesare arranged symmetrically with respect to a center line extending in alongitudinal direction of said opening.
 3. The method according to claim1, wherein said etching mask layer is formed such that a length Y (μm)of said opening to be formed, measured in a widthwise direction thereof,satisfies(T/tan 54.7°)×2+L≧Y.
 4. The method according to claim 1, wherein aforming condition of said recesses is changed depending on a thicknessof said substrate measured beforehand.
 5. The method according to claim4, wherein a depth of said recesses is changed depending on a thicknessof said substrate measured beforehand.
 6. The method according to claim4, wherein a distance from a center line of said area extending in alongitudinal direction of said area to centers of said recesses in therows is changed depending on a thickness of said substrate measuredbeforehand.
 7. The method according to claim 1, wherein there areprovided a plurality of such openings which are formed adjacent to eachother in a widthwise direction of said opening, and wherein dimensionsof adjacent openings are different from each other.
 8. The methodaccording to claim 7, wherein a dimension Y1 of one of said adjacentopenings measured in a widthwise direction thereof, and a dimension Y2of the other one of said adjacent openings measured in a widthwisedirection thereof satisfy,(T/tan 54.7°)×2+L≧Y1,(T/tan 54.7°)×2+L≧Y2, andY1>Y2, or Y2<Y1.
 9. The method according to claim 1, further comprisinga step of forming a passivation layer having an etching-resistantproperty so as to cover said sacrificial layer.
 10. The method accordingto claim 1, wherein said recesses are formed by laser.